Field of the Invention
The present invention relates to an image processing apparatus, an information processing method, and a storage medium.
Description of the Related Art
Recently, attention has been paid to an Internet Protocol facsimile (IPFAX) that transmits and receives a facsimile (FAX) via an Internet Protocol (IP) network.
The Session Initiation Protocol (SIP) is used for a call connection between IPFAX devices, and the T.38 protocol for data communication. An IPFAX using the T.38 protocol, which can perform communication faster than a conventional analog FAX, can transmit and receive an image in a shorter time.
The IPFAX performs FAX communication between devices connected to an intranet (local IP network) or FAX communication between devices connected to a public IP network.
Communication within an intranet, which uses a company network or a local network for communication, does not involve communication fees.
On the other hand, communication on a public IP network, like communication on an existing analog public network, employs a pay-per system that involves a fee for each FAX communication.
Conventional IPFAX devices cannot be connected to the two types of IP network, i.e., local and public IP networks, at the same time. Therefore, conventional IPFAX can operate in any one of the two modes (local IP network mode and public IP network mode) selected according to a setting made by a user, or can operate only in one of the two modes.
In recent years, as a network has become diversified, there has been a need for an IPFAX device that can communicate with any of a device on a local IP network and a device on a public IP network without requiring a user to change the user setting.
According to the SIP protocol for call connections, an INVITE message is used to request a connection. An INVITE message includes a description described in Session Description Protocol (SDP) (See Japanese Patent Application Laid-Open No. 2012-90213).
The SDP is a protocol used to describe a multimedia session. For example, the SDP is used to describe information about the type of media to be communicated, that is, whether an audio is to be communicated (audio), whether an image is to be communicated (image, application), and whether a video is to be communicated (video). The media type (m) is used to determine what is to be communicated. Normally, “m=audio” is specified for IP telephony, and “m=image” or “m=application” is specified for IPFAX via a public IP network.
Because T.38 IPFAX usually does not provide the phone function, it is desirable to reject an INVITE message received from a phone. In particular, on a public IP network, a caller is charged for a call in spite of the fact that communication cannot be performed. To address this problem, in a conventional method, the media type “m=audio” is rejected but the media type “m=image” or “m=application” is accepted.
However, when IPFAX communication is performed via a local IP network, a message is transmitted usually via an SIP server that has a routing function and a registration function. This sometimes requires the user to follow a specific procedure depending on the type of the SIP server.
For example, the SIP server provided by a company requires a procedure in which “audio” is specified for the SDP media type of a first INVITE message, and after that, the media type is changed to “image”. Therefore, if all INVITE messages are simply rejected because the media type is “audio”, there is an issue that IPFAX communication cannot be performed via a local IP network.
There is a T.38 gateway (T.38 GW) capable of connecting an analog FAX to an IP network as an IPFAX. However, the T.38 GW provided by a company transmits an INVITE message in which “audio” is specified for the media type as described above. Normally, the T.38 GW is connected to a local IP network.